Stabilized propellent compositions containing hydrazine nitroform and nitrocellulose



United States Patent Ofilice 3,37,985 latented Mar. 7, 1967 3,307,985STABILIZED PROPELLENT COMPOSITIONS CONTAINING HYDRAZTNE NITROFORM ANDNITROCELLULOSE William H. Jago, Washington, D.C., assignor to AtlanticResearch Corporation, Fairfax County, Va., 21 corporation of Virginia NoDrawing. Filed July 6, 1961, Ser. No. 125,62 9 Claims. (Cl. 149-18) Thisinvention relates to new propellent compositions. More specifically, itrelates to propellents comprising a mixture of nitrocellulose andhydrazine nitroform, which are characterized by greatly improvedstability.

There have recently been introduced into the propellant art high impulsepropellent compositions comprising nitrocellulose and hydrazinenitroform, in which the nitrocellulose, preferably plasticized, servesas a gas-generating fuel binder, and the hydrazine nitroform isdispersed therein and functions as an oxidizer and gas-generatingcompound.

Both nitrocellulose and hydrazine nitroform tend to degrade with theproduction of gaseous by-products, unless stabilized. Stabilizers foreach of the compounds in dividually are known in the art. Stabilizersfor nitro' cellulose include, for example, ethyl centralite,2-nitrodiphenyl amine, magnesium oxide and magnesium. Hydrazinenitroform stabilizers include, for example, mercuric oxalate, P andoxalic acid. Unfortunately, it has been found that stabilizers hithertoeliective with nitrocellulose tend to degrade the hydrazine nitroformand vice versa.

The object of this invention is to provide stabilizers which areeffective for both the nitrocellulose and hydrazine nitroform inadmixture.

I have discovered that the salts of a Group II-A metal, such asberyllium, magnesium, calcium, barium and strontium, very eifectivelystabilize mixtures of nitrocellulose and hydrazine nitroform. Themechanism of such stabilizers is not entirely understood, but it isbelieved that the cation stabilizes the nitrocellulose component, andthe anion stabilizes the hydrazine nitroform.

The anion can be an inorganic or organic radical, such as sulfate,bisulfate, sulfite, bisulfite, nitrate, nitrite, phos phate, hydrogenphosphate, carbonate, bicarbonate, chloride, acetate, oxalate, tartrate,lactate and benzoate.

The Group Il-A metal salts are effective in amounts as low as 0.05% byweight of the propellent composition. Amounts up to l or 2% aregenerally completely adequate. Above these rates of addition, somefurther improvement in stabilization can be obtained, but atprogressively smaller increments relative to the percentage ofstabilizer addition. In general, it will not be desirable to add morethan about of the stabilizer since, beyond this point, furtherimprovement in stability, if any, is so minimal as not to warrantfurther addition of a component which is ballistically inert.

Plasticizers for the nitrocellulose, both active and inert,conventionally employed in the nitrocellulose propellant art, can beincluded in the compositions.

The term active, as employed herein, refers to compounds which contain amolecularly-combined oxidizing element, such as oxygen or fluorine,which is available for combustion of other molecularly-combinedcomponents, such as carbon and hydrogen. Such plasticizers include, forexample, liquid, organic polynitrates such as nitroglycerine,trimethylol ethane trinitrate, *triethylene glycol dinitrate,pentaerythritol trinitrate and the like.

The liquid plasticizer can also be, in whole, or in admixturewith anactive plasticizer as above defined, a high-boiling organic liquid,which is inert inasmuch as it requires an external or separate source ofoxidizer for combustion. Examples of such suitable liquidplasticizersinclude hydrocarbons, e.g. triethyl benzene, dodecane, phenylxylylethane; esters, e.g. butyl laurate, dibutyl phthalate, triacetin,tributyl acetyl citrate, dioctyl adipate, etc.; alcohols, e.g. benzylalcohol, diethylene glycol, triethylene glycol, etc.; ethers, e.g.bis(dimethyl benzyl) ether; propylene glycol monobutyl ether, etc.;ketones, e.g. isophorone; acids, e.g. caproic acid, n-heptylic acid;aldehydes, e.g. cinnamaldehyde; nitrogen-containing organic compoundssuch as nitriles, e.g. adiponitrile; phosphorous-containing compounds,e.g. tricresyl phosphate; sulphur-containing compounds, e.g.N-ethyl-toluene sulfonamide; and many others. Such inert organic liquidplasticizers function as a fuel component when adequate oxidizer, suchas the hydrazine nitroform, is included to provide for their combustion.

Of particular importance because of their high performance, arenitrocellulose-hydrazine nitroform propellent compositions which containa powdered metal fuel component, such as aluminum, magnesium, beryllium,boron, zirconium and their hydrides. The hydrazine nitroform functionsas oxidizer for these fuels. Other insoluble solid fuel components canalso be dispersed in the nitrocellulose-hydrazine nitroform propellants,such as carbon, silicon and the like.

The relative proportions of the components such as nitrocellulose,plasticizer, hydrazine nitroform, metal and the like vary for differentapplications according to required performance. Such variations areknown to, and can readily be calculated by, those skilled in thepropellant art. The amount of hydrazine nitroform, for example, must besufiicient to provide for combustion of inert components of thecomposition, such as metal fuel and inert plasticizer, but the actualamount required will be determined by the particular inert components,their concentrations, and the desired level of performance.

Example I Tests were made to determine the stabilizing effect of variousGroup II-A metal salts. The following propellent compositions wereprepared:

Decomposition of the control and test samples into gaseous products wasdetermined by Taliani test as described in NavOrd Report No. 5688,entitled Taliani Tests for Assessment of Stability of Solid Propellants5% MgCO on the propellent composition of Example I. TechnicalInformation Agency.

Pressure, Increase in Time, Min. cm. Hg pressure,

cm. Hg

(A) C ONT ROL (B) MgCOs ga(PO7) (D) MgSOi 0 33. 1 5 39. 4 6. 3 10 42. 39. 2 15 43. 1 10. 0 20 44. 1 11. O 25 44. 8 l1. 7 30 45. 5 12. 4 35 46.3 13. Z 40 46. 9 13. 8 45 47. 4 14. 3

(E) MgHPOi (F) Mg(OO CCHa)2 0 35. 7 5 40. 8 5. 1 10 42. G 6. 7 15 43. 57. 6 2O 44. 1 8. 2 25 44. 6 8. 7 30 45. 2 9. 3 35 45. 8 9. 9 40 46. 210. 3 45 46. t) 10. 7

Pressure, Increase in Time, Min. cm. Hg pressure,

em. Hg

(H) BG(NO3)2 I will be noted from the foregoing that all of the GroupII-A salts tested were exceedingly effective in stabilizing thenitrocellulose-hydrazine nitroform compositions.

Example II A test was made to determine the stabilizing effect of 5%MgCOon the propellent composition of Example I. The concentration ofaluminum was reduced to 15%. Taliani test results were as follows:

Pressure, Increase in Time, Min. em. Hg pressure,

cm. Hg

Although this invention has been described with reference toillustrative embodiments thereof, it will be apparent to those skilledin the art that the principles of this invention may be embodied inother forms but within the scope of the appended claims.

I claim:

1. In a propellent composition comprising nitrocellulose and hydrazinenitroform, the improvement comprising the addition of up to about 10% byweight of a salt of a Group II-A metal, said salt serving to stabilizesaid nitrocellulose and hydrazine nitroform.

2. The propellent composition of claim 1 which contains in addition aplasticizer for the nitrocellulose and a finely-divided solid fuelcomponent selected from the group consisting of metals, metal hydrides,carbon and silicon.

3. The propellent composition of claim 2 in which the solid fuel isaluminum.

4. The propellent composition of claim 1 in which the salt is amagnesium salt.

5. The propellent composition of claim 1 in which the salt is aberyllium salt.

6. The propellent composition of claim 1 in which the salt is a calciumsalt.

7. The propellent composition of claim 2 in which the salt is amagnesium salt.

8. The propellent composition of claim 2 in which the salt is aberyllium salt.

9. The propellent composition of claim 2 in which the salt is a calciumsalt.

No references cited.

CARL D. QUARFORTH, Primary Examiner.

ROGER L. CAMPBELL, OSCAR R. VERTIZ,

Examiners.

B. R. PADGETT, Assistant Examiner.

1. IN A PROPELLENT COMPOSITION COMPRISING NITROCELLULOSE AND HYDRAZINENITROFORM, THE IMPROVEMENT COMPRISING THE ADDITION OF UP TO ABOUT 10% BYWEIGHT OF A SALT OF A GROUP II-A METAL, SAID SALT SERVING TO STABILIZESAID NITROCELLULOSE AND HYDRAZINE NITROFORM.